Three Chinese tourists were killed and another badly injured when their sports utility vehicle and a loaded trailer truck collided at an intersection in Klaeng district of Rayong in the early hours of Wednesday.
The fatal crash occurred at Krasaebon intersection on Highway 344, on the Ban Bueng-Klaeng stretch to downtown Klaeng district.
It was reported to police about 1.30am, according to Pol Lt Pongphon Chantra, deputy investigation inspector.
Emergency responders reported finding an overturned 18-wheel truck loaded with sand and a crushed Toyota Fortuner at the scene. They could hear groans of pain from inside the Fortuner.
A crane was used to lift the truck off the Fortuner, and rescuers then used cutting equipment and levers to prise open the wreckage and extract the trapped victims.
The driver, a 38-year-old Chinese national, was alive but badly hurt and was rushed to Klaeng Hospital. His three passengers were dead - Chinese nationals aged 39, 40 and 49 years.
Police investigators learned that the Fortuner had stopped at the traffic lights. The driver made a right turn and the vehicle was hit by the oncoming trailer truck. The Fortuner was dragged about 50 metres along the road before the truck came to a stop.
The 18-wheeler driver fled the crash scene.
Investigators were examining surveillance video footage from the scene and said they would find the fleeing driver.
The Chinese embassy had been informed, police said.